1. Field of the Invention
The present invention relates to a calendar mechanism equipped timepiece which displays the date with two date indicators. More particularly, the invention relates to a calendar mechanism equipped timepiece including a first date indicator, which displays the ones column of the date, a second date indicator, which displays the tenths column of the date, and a program wheel for advancing the first date indicator and second date indicator.
2. Description of the Related Art
(1) Description of Terminology:
In general, a mechanical body including the drive portion of a timepiece is referred to as a “movement”. A condition in which a dial and hands are mounted on the movement, and housed in a timepiece case, thus forming a completed product is referred to as a “complete” of the timepiece. Of the two sides of a main plate configuring the substrate of the timepiece, a side on which glass of the timepiece case exists, that is, a side on which the dial exists, is referred to as the “back side”, “glass side”, or “dial side” of the movement. Of the two sides of the main plate, a side on which the case back of the timepiece case exists, that is, the side opposite to that of the dial, is referred to as the “front side” or “back case side” of the movement. A train wheel mounted on the “front side” of the movement is referred to as a “front train wheel”. A train wheel mounted on the “back side” of the movement is referred to as a “back train wheel”. In general, a “12 o'clock side” refers, in an analog timepiece, to a side on which a calibration corresponding to 12 o'clock on the dial is disposed. A “12 o'clock direction” refers, in the analog timepiece, to a direction toward the “12 o'clock side” from the rotation center of the hands. Also, a “3 o'clock side” refers, in the analog timepiece, to a side on which a calibration corresponding to 3 o'clock on the dial is disposed. A “3 o'clock direction” refers, in the analog timepiece, to a direction toward the “3 o'clock side” from the rotation center of the hands. Also, a “6 o'clock side” refers, in the analog timepiece, to a side on which a calibration corresponding to 6 o'clock on the dial is disposed. A “6 o'clock direction” refers, in the analog timepiece, to a direction toward the “6 o'clock side” from the rotation center of the hands. Also, a “9 o'clock side” refers, in the analog timepiece, to a side on which a calibration corresponding to 9 o'clock on the dial is disposed. A “9 o'clock direction” refers, in the analog timepiece, to a direction toward the “9 o'clock side” from the rotation center of the hands. Furthermore, there may be a case in which other sides, such as a “2 o'clock direction” and a “2 o'clock side”, refer to sides on which other calibrations on the dial are disposed.
(2) Heretofore Known Calendar Mechanism Equipped Timepiece:
Hereafter, a description will be given of a configuration of a heretofore known calendar mechanism equipped timepiece including a first date indicator, which displays the ones column of the date, and a second date indicator, which displays the tenths column of the date.
(2•1) Heretofore Known First Type Calendar Mechanism Equipped Timepiece:
A heretofore known first type calendar mechanism equipped timepiece, including a ones column movable portion interlocking with a ones column star having ten teeth, and a tenths column movable portion interlocking with a tenths column star having four teeth, is configured so that the ones column star and tenths column star are directly driven by a ones column internal gear and a tenths column internal gear, provided one on each coronal gear (See, for example, Japanese Patent No. 3,322,678).
(2•2) Heretofore Known Second Type Calendar Mechanism Equipped Timepiece:
A heretofore known second type calendar mechanism equipped timepiece includes two date indicators, that is, a first date indicator and a second date indicator, which at least partially overlap each other. The first date indicator provides a ones column date display, and the second date indicator provides a tenths column date display. Numbers “0” and “1” to “9”, that is, ten numbers are circumferentially provided on the first date indicator. Two sets of numbers “0” to “3”, that is, eight numbers are circumferentially provided on the second date indicator. A drive mechanism includes a 24 hour wheel, which rotates once every 24 hours by means of the rotation of an hour wheel, an operation lever operated by means of the rotation of the 24 hour wheel, other control gears, and the like. A program wheel rotates by means of the operation of the operation lever, a first date indicator drive wheel rotates the first date indicator, and a second date indicator drive wheel rotates the second date indicator. The rotation of the first date indicator is set by a first date indicator jumper. The rotation of the second date indicator is set by a second date indicator jumper (See, for example, EP-A-1070996 A1).
(2•3) Heretofore Known Third Type Calendar Mechanism Equipped Timepiece:
A heretofore known third type calendar mechanism equipped timepiece includes a ones column disc, which displays the ones column of the date, and a tenths column disc, which displays the tenths column of the date. A ones column pinion is fixed to the ones column disc. A ones column jumper maintains the angular position of the ones column pinion. A tenths column pinion is fixed to the tenths column disc. A tenths column jumper maintains the angular position of the tenths column pinion. The ones column pinion meshes with the upper half of the tooth row of a date gear. Numbers “0” and “1” to “9”, that is, ten numbers are circumferentially provided on the ones column disc. Two sets of numbers “0” to “3” and two “0”s, that is, ten numbers are circumferentially provided on the tenths column disc. Each hook of a drive device meshes with the tooth row of the date gear, thereby causing the teeth of the date gear to advance one step a day. The tenths column pinion is driven step by step by an intermediate movable part. The intermediate movable part is driven step by step via an idle gear by the date gear (See, for example, JP-A-2000-147148).
(2•4) Heretofore Known Fourth Type Calendar Mechanism Equipped Timepiece:
A heretofore known fourth type calendar mechanism equipped timepiece includes a first date indicator and a second date indicator, which display the ones column of the date, a third date indicator, which displays the tenths column of the date, and a program wheel, which can cause each of the first date indicator, second date indicator, and third date indicator to rotate intermittently based on the operation of a drive mechanism. It is possible to display the date with one of first date characters of the first date indicator and one of third date characters of the third date indicator, and display the date with one of second date characters of the second date indicator and one of the third date characters of the third date indicator (See, for example, JP-A-2007-93591).
With the heretofore known first type calendar mechanism equipped timepiece, a configuration is such that, the height of the coronal gear being two-tiered, the second date indicator is advanced by the lower gear, and the first date indicator is advanced by the upper gear. Furthermore, the teeth of the program wheel are below the lower gear, thus forming a three-layer structure as a whole. For this reason, there has been a problem in that the number of parts becomes larger, and the timepiece becomes thicker.
With the heretofore known second type calendar mechanism equipped timepiece, as a gear which advances the ones column date and a gear, which advances the tenths column date are stacked one on the other, there has been a problem in that the timepiece becomes thicker. With this type of calendar mechanism equipped timepiece, as a ones column date display plate and a tenths column date display plate are stacked one on the other, there has been a problem in that the timepiece becomes still thicker. With this type of calendar mechanism equipped timepiece, the program wheel is rotated one tooth via the operation lever 44 by a lever drive pin 46 provided on a date indicator driving wheel 48. Consequently, there has been a problem in that the drive mechanism is complex, and the area occupied by the drive mechanism becomes larger.
With the heretofore known third type calendar mechanism equipped timepiece, as the tenths column pinion is driven by the date gear via the intermediate movable part and idle gear, there has been a problem in that the drive mechanism for driving the tenths column disc is complex, and the area occupied by the drive mechanism becomes larger.
With the heretofore known fourth type calendar mechanism equipped timepiece, as it includes the first date indicator and second date indicator, which display the ones column of the date, and the third date indicator, which displays the tenths column of the date, there has been a problem in that the number of parts becomes larger, and the timepiece becomes thicker.
Furthermore, the heretofore known calendar mechanism equipped timepiece has had a problem in that the drive mechanism is complex, and the rotational load of the drive mechanism is large. Also, with the heretofore known calendar mechanism equipped timepiece, as numbers indicating ten days are provided in the circumferential direction of a date indicator, it has been difficult to increase the dimension of the numbers indicating the days.